Certain underwater areas of harbors, inlets or other waterways must periodically be dredged of sand or other solid material so as to maintain a certain depth of the waterbed for the safe passage of water craft. These channels or other harbor areas continually fill with sand due to the wave action tide or the like and heretofore it has been the practice to periodically clear the area when the height of the solid material reached a certain level. This periodic cleaning of the areas was not satisfactory because of time and effort required to set and remove the dredging equipment, and furthermore because of the different and varying time intervals required for the area to become filled with sand to a point where it must be cleared out. Another shortcoming of this prior art dredging process was that it was not done uniformly and to the same extent each time, resulting in unpredictable safe passage of the water craft. Certain areas of the harbor, channel or inlet waterways became filled more rapidly then others and these particular areas required more frequent attention.